Residual feed intake in dairy ewes: an evidence of intraflock variability

Abstract

6 7 8 a Abstract 9 This study examined the intraflock variability of feed efficiency in dairy ewes, through 1 0 monitoring residual feed intakes (RFI). Primiparous lactating ewes (n=43; 57.7±0.91 kg body 1 1 weight [BW] at lambing), representative of a French Lacaune dairy flock, were allocated in an 1 2 equilibrated 2 × 2 factorial design experiment, lasting for 63 days during mid-lactation and 1 3 combining 2 litter sizes (singletons, SING or twins, TWIN) and 2 daily milking frequencies (once, 1 4 ONE or twice, TWO). Ewes were individually fed a diet based on ryegrass silage, local hay and 1 5 supplements. Individual DMI was recorded daily and further used to evaluate (and compare) 1 6differences in RFI between ewes at 35, 42, 49, 56, 63, 70, 77, 84, 91 and 98 days relative to 1 7 lambing (DIM). Total (BW) and metabolic (BW 0.75 ) body weight, BCS, milk yield and plasma 1 8 NEFA were monitored weekly. Differences in DMI were mainly due to the lactation stage and 1 9

Effect of Dietary Supplementation with Lipids of Different Unsaturation Degree on Feed Efficiency and Milk Fatty Acid Profile in Dairy Sheep

“…In the last years, an increasing number of researchers in ruminant nutrition have turned their efforts towards prioritizing an improvement in feed efficiency over production level [ 17 , 18 , 19 ]. Although there is still very little information on this topic, particularly in dairy ewes [ 20 , 21 ], a recent study has suggested a relationship between feed efficiency and lipid metabolism in the ovine, with certain milk FA being potential biomarkers of this trait (e.g., saturated C4–C14 FA, saturated C4–C14 fatty acids/ cis -9 18:1 ratio, or C20–22 n-6 polyunsaturated FA) [ 22 ]. Thus, because diet composition has a great influence on the efficiency of feed utilization [ 19 , 23 , 24 ], re-evaluation of the use of lipid supplements aimed at improving milk FA composition is required to examine their effects on metrics and biomarkers of feed efficiency.…”